Solubilization and delivery of hydrophobic drugs is one of the most challenging issues in pharmaceutical formulation, particularly since most drugs are hydrophobic. Such drugs tend to precipitate in an aqueous environment, such as the bloodstream. Whether the drug is delivered by oral or parenteral routes, a certain level of aqueous solubility is required for adequate absorption and bioavailability. Pharmaceutical grade surfactants, such as Tween® 80 or Cremophor®, have been widely used in formulations to compensate for the low aqueous solubility of hydrophobic drugs. These surfactants solubilize hydrophobic drugs by forming micellar structures in aqueous media. Unfortunately, these surfactants have been associated with severe allergic reactions and hypersensitivity when administered to patients (Kris, et al., Cancer Treatment REP, 70:5, (1986)). After parenteral administration, these micellar drug carriers disintegrate when the concentration is below their critical micelle concentration (CMC), resulting in a rapid release of the drug. That is to say, in addition to the possibility of adverse side effects upon administration, conventional surfactant-based carriers also lack the ability to provide controlled release of a drug.
Thus, there remains a need in the art for a method for imparting adequate levels of aqueous solubility to a hydrophobic drug such that the drug may be administered in a therapeutically effective manner.